Lithographic or offset printing plate



June 21, 1932.

F. FISCHER LITHOGRAPHIC OR OFFSET PRINTING PLATE Filed Dec. 16, 1929 Era 1 11 Q/zq/ 786Aer /n venfor':

Patented June 21, 1932 PATENT OFFICE FERDINAND FISCHER, OF BERLIN, GERMANY LITHOGRAPHIC OR OFFSET PRINTING PLATE Application filed December 16, 1929, Serial No. 414,570, and in Germany December 24 1 928.

- the former the common disadvantage of occupying considerable time.

In order to eliminate the disadvantages of these methods and to render the production of printing plates as economical as possible,

' according to the present invention, whilst utilizing an existlng, previously prepared working mould, the surface grain is imparted to the printing plate by plastic moulding.

For example, the graining is imparted to the printing plate by a pressing or rolling impression of a grained working surface. A printing plate of mouldable material thus receives a surface grain effect dependent upon the grain of the workin surface. The advantage of this method is as follows :-The graining of all printing plates produced with the same working surface is absolutely equal and if certain spheres of utility require another form of graining it is merely necessary to use another working surface.

The graining may also be effected, clearly defined locally, only on certain parts of the printing plate and the -graining only takes a minimum amount of time and is much cheaper than all the methods hitherto customary. As working surface a level grained surface may be used which is applied by stamping or pressin or a suitable roller may be used which rol sits grain on. The graining of the printing plate can be effected on one or both sides. The latter method is particularly adopted in the case of thin printing sheets of office machines (see German Patents 204,517 and 410,168), the graining being used to impart a better hold for the glue (or size) of printing-plates coated at the back with paper or the like. Instead ofa pastedon coating, similarly acting materials, such as celluloid, varnished surfaces and the like may also be applied to the grained rear side.

In the accompanying drawings, which illustrate two forms of my invention by way of example, Figs. 1 and 2 are respectively perspective views of different forms of the invention. I

.In Fig. 1, a long web or ribbon of extremely thin lithographic metal is shown at 1, together with a base plate or lower die 2. The upper die 3 is preferably provided with a -grained or roughened surface 4. Now if the die 3 is depressed upon the web 1 periodically, grained surfaces 7 are formed upon the web 1. Obviously, if the lower die 2 is also provided with a grained or roughened surface, corresponding grained surfaces 7 will also be formed on the back face of the web 1.

Fig. 2 is almost identical with Fig. 1 except that the dies 2 and 3 are replaced by rollers 5 and 6.

\Vhat I claim is 1. In the manufacture of lithographic printing plates of moldable material, the step of graining the face and the back of the plate by a pressing action producing a large number of depressions simultaneously.

2. In the manufacture of lithographic printing plates of moldable material, the step of graining the face and the back of the plate by a pressing action producing a large number of depressions simultaneously and applying acoating to said grained back.

In testimony whereof I affix my signature.

FERDINAND FISCHER.

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